How to use the Nios DMA?

Here is soft for using DMA on NIOS2

void memcpy_my(int *where,int * from,int howmurch)

{

while ((IORD_ALTERA_AVALON_DMA_STATUS(WR_DMA_BASE) & ALTERA_AVALON_DMA_STATUS_BUSY_MSK));

IOWR_ALTERA_AVALON_DMA_CONTROL(WR_DMA_BASE,0);

IOWR_ALTERA_AVALON_DMA_STATUS(WR_DMA_BASE, 0);

IOWR_ALTERA_AVALON_DMA_LENGTH(WR_DMA_BASE, howmurch);

IOWR_ALTERA_AVALON_DMA_RADDRESS(WR_DMA_BASE, from);

IOWR_ALTERA_AVALON_DMA_WADDRESS(WR_DMA_BASE, where);

IOWR_ALTERA_AVALON_DMA_CONTROL(WR_DMA_BASE,ALTERA_AVALON_DMA_CONTROL_GO_MSK |

ALTERA_AVALON_DMA_CONTROL_BYTE_MSK|

ALTERA_AVALON_DMA_CONTROL_WEEN_MSK|

ALTERA_AVALON_DMA_CONTROL_LEEN_MSK);

while ((IORD_ALTERA_AVALON_DMA_STATUS(WR_DMA_BASE) & ALTERA_AVALON_DMA_STATUS_BUSY_MSK));# ifdef DEBUG

printf("\nDMA packet\nfrom 0x%x\nwhere - 0x%x\nhowmurch - %d",from,where,howmurch);

short status=0;# endif

}